Brachystelma foetidum is a perennial herbaceous geophyte belonging to the Apocynaceae family, which grows up to 150 mm, depending on the climate and conditions of the area. The stem is 60 to 150 mm long, and grows from a flattened underground tuber which is 15 to 200 mm in size, but its size varies with the age of plant, older plants having larger tubers. The upper surface of the tuber is concave, whereas the under surface is convex. It has fibrous roots that are produced from the side and base of the tuber. The inner part of the tuber is made up of a white, potato-like tissue.

Usually the plant is dormant in winter and resprouts with 1 or many new stems in spring. The leaves are simple, opposite, linear-lanceolate or elliptic, about 30 mm long and 10 mm broad, green, hairy, with wavy margins and narrowing to a short petiole. The flowers vary in size and 2–6 are produced together. They are bell-shaped with elongated lobes of purple-brown, greenish yellow near the base, with purple-brown spots. They are attractive but have a very unpleasant smell. Out of all species in the genus Brachystelma, B. foetidum has the most unmistakable flower because of its foul smell. It flowers from late spring to summer (October to February).

The seeds are light brown to dark brown, with a very narrow marginal wing along the edge. At the end of the seeds there is a parachute of white fluffy hairs, which allow the seeds to be dispersed easily by wind. Most of the species in the Apocynaceae,employ this airborne method of seed dispersal.